Internal combustion engines include crankcases having a plurality of cylinders. The cylinders contain pistons whose reciprocating motion due to combustion events that occur in a variable volume within a plurality of bores in the crankcase that contain the pistons, and the pistons themselves, may be transferred through a crankshaft to yield a torque output of the engine. Often, engine crankcases are made of cast metal, and include passages integrally formed therein for the transfer of various fluids from one location of the engine to another. Fluids typically transferred through passages in an engine include coolant, air, fuel, oil, gases, vapors, and so forth.
During operation of the engine, a mixture of air and fuel combusts in a cylinder, and exhaust gas that is produced by the combustion is released therefrom through one or more exhaust valves. Sometimes, a small quantity of exhaust gas may escape through a seal between the piston and the bore, and enter an internal volume of the crankcase. This small amount of exhaust gas is commonly referred to as “crankcase gas”. The crankcase gas is typically allowed to exit the crankcase in a controlled fashion, and is usually recirculated into the intake system of the engine. Crankcase gas often includes some amount of lubrication oil of the engine. This amount of oil is either vaporized and/or splashed by various engine components during operation, or is just picked up when it sublimes due to heat by the crankcase gas in droplet or gas form as the crankcase gas travels through the crankcase. Devices called “breathers” are used to remove oil from the crankcase gas before it's recirculated into the intake of the engine.
A typical breather device may include a filter or another method that removes oil from the crankcase gas. The more oil that is included in the crankcase gas, the larger and more costly the breather must be to effectively remove the oil that is included in the crankcase gas. Use of breathers is often determined by the size of the engine and the cylinder pressures during combustion. For larger engines, or engines having comparatively high cylinder pressures during operation, for example diesel engines, breathers may become large and costly.
Accordingly, there is a need for an ability to decrease the amount of oil carried with the crankcase gas before the gas reaches the breather, in order to decrease the size and increase the effectiveness of a breather for an engine that would otherwise require a larger breather device. The smaller breather would be easier to fit onto the engine, less costly, and more effective than a breather that would typically be required.